Yǐn Xǐ 尹喜 (zì Gōngdù 公度, hào Wénshǐ xiānshēng 文始先生) — the Warring-States-period keeper of the Hángǔ Pass 函谷關 who, according to the tradition preserved in Shǐjì 63 (Lǎozǐ zhuan) and enlarged in later Daoist biography, detained the emigrating Lǎozǐ 老子 at his pass and there received from him the Dàodé jīng 道德經. Yǐn Xǐ thereafter became Lǎozǐ’s chief disciple and accompanied him westward into the Hú 胡 lands (cf. the huàhú 化胡 tradition, where Yǐn Xǐ is identified, at Lǎozǐ-as-Buddha’s side, with Ānanda). As Guānyǐn 關尹 (“Passkeeper-Yǐn”), he is the title-figure of the Guānyǐnzǐ 關尹子 (also called Wénshǐ zhēnjīng 文始真經), an early philosophical work listed as nine piān in the Hànshū yìwénzhì 漢書藝文志 30.1730 but surviving only in later recensions (see DZ 667, KR5c0048); the received text is a 12th-century compilation.
In the religious tradition, Yǐn Xǐ is canonised as Wúshàng zhēnrén 無上真人 (Supreme Perfected) and Wénshǐ zhēnrén 文始真人 (Perfected of the Pattern’s Beginning). He is the tutelary figure of Lóu guàn 樓觀 on Zhōngnán shān 終南山, traditionally his residence after Lǎozǐ’s departure. Lóu guàn became a major Daoist institutional centre from the early Táng onward, and in the Quánzhēn 全真 school of the Yuán Yǐn Xǐ was reclaimed as a patriarch-figure: the Quánzhēn tradition celebrates the year 1233 as the date when the long-lost Wénshǐ zhēnjīng was brought to Yǐn Zhìpíng 尹志平 (a descendant of the Yǐn clan) on Zhōngnán shān by one Zhāng Zhòngcái 張中材 of Zhèjiāng (see Dà Yuán chóng xiū gǔ Lóu guàn zōng shèng gōng jì 大元重修古樓觀宗聖宮記).
Historical lifedates cannot be assigned with any confidence; the traditional dates place Yǐn Xǐ as a contemporary of Lǎozǐ in the late Western Zhōu or Spring and Autumn period. For works in the Kanripo corpus attributed to Yǐn Xǐ, see KR5c0048 (Wúshàng miàodào wénshǐ zhēn jīng, pseudepigraphic, 12th cent.).